The current method of RF wiring in today's′ personal computers, cell phones, and tablet PCs—although continually improved by companies around the world, still remains with many problems in design, difficulty of manufacture, non-ideal performance in many RF design areas. The entire WiFi and WWAN world has gradually, incrementally, improved many of these areas, including RF connector and coaxial wire design, but several problem areas still remain. Additionally, the ‘mini’ and ‘micro’ coaxial wiring / RF radio industry seems to be stalled in a paradigm of what wire is currently used, and how the antennas are supplied—commonly with wire ‘tails’. Moreover, when one enters the world of Tablet PCs, the design and manufacturing problems, errors get even more numerous. The following are examples of limitations of using micro-wire (UFL/MHF) connections. UFL connectors are also known as U.FL and/or uFL and/or Ufl and/or u.fl and/or ufl connectors.
FIG. 1 illustrates a prior art mobile device 10 showing a typical arrangement of micro-wire coaxial cables 12 and 14 routing connections to multiple wireless radios 16 and antennas 22 and 24. The routing is not optimal and require being handled multiple times as parts are added. Some of these connections such as WWAN Main and WWAN Auxiliary connections must be routed outside the devices EMI shield 18 because the shielding of even the better quality prior art 1.32/1.37 mm Micro-wire coaxial cable is inadequate to protect the devices circuitry from the WWAN signals coursing trough the micro-wire. The routing of these micro-wires 12 and 14 are typically not uniform from device to device. Typically they are somewhat randomly taped in place. Even the connectors may not be attached in a uniform manner. Typically the micro-wire have male parts of a male female pairs of UFL (or alternatively IPEX, IPAX, MHF or AMC connectors) examples of which are available from Hirose of Japan. The connectors are characteristically round and do not register in a particular rotational position. The Receiver and/or transmitter circuit board and antennas typically has the female part of the UFL mail female connector pair which provides the connection port to which the micro wire is connected.
FIG. 2 is an illustration of another view of the device in FIG. 1 showing the routing of other micro-wire coaxial cables 32, 34, 36 to their respective antennas 42, 44, 46. While this is routing is more consistent and optimal than the WWAN routing illustrated in FIG. 1, the routing nevertheless posses manufacturing and repair problems due to kinking, pinching during manufacture use and/or repair of the device 10 these risk also cause problems with the micro-wires 12, 14 illustrated in FIG. 1.
FIG. 3 illustrates an exemplar mobile computing device. Including circuit boards that contain circuitry 16 designed to either generate RF signals for transmission or process received RF signals. It also contains antennas 22 and 24 that are specifically designed to send and or receive particular frequencies or frequency bands or combinations of frequencies or frequency bands. Examples include any wide area networks either local “WLAN” or wireless “WWLAN” blue tooth, GPS etc—basically any kind of electromagnetic transmission capable of being transmitted or received by an antenna.
FIG. 4 illustrates an example of a typical micro-wire 52. A typical micro wire has three major sections. The conductive wire itself 54 and two connects which were described above.
FIG. 5 illustrates a cross section of the conductive wire of the micro-wire. These wires are coaxial having a center core made of electrically conductor 58 typically a copper wire, surrounded by a nonconductive dielectric 60 which by definition is non-electrically conductive. The inner dielectric is surrounded by a braded shield 62 made of a conductive material for example copper or stainless steel. The shield is typically covered with another dielectric insulation layer 64.
These Micro-Wires are typically made with polymer dielectrics which result in a soft core so the wires are soft, squishy and deformable. These materials make the micro-wires easier to rout however it also makes them more likely to get pinched, kinked and deformed. When the wire is pinched VSWR performance is compromised causing signal reflection, waste and detuning of the cable). Thus more care is required in the manufacture and repair of products using the wire and thus in the design in the product resulting in design limitations caused by using the micro-wire.
Low EMI Noise is very important in many products. Thus WWAN TIS (Total Isotropic Sensitivity) is very important to these products. New EMI regulatory specifications have made it more difficult to comply with wireless noise specifications EMI Noise couples into coaxial wires to varying degrees requiring thinner micro-wire.
Micro-Wire's E-field shielding only provides about eight to eighty-five percent (80-85%) shielding effectiveness (SEE=15 dB). For WWAN cell phone TIS EMI testing, this poor performance frequently requires additional external shielding to further shielding U/FL wire.
Woven Braided Shield typically found in micro-wire frequently is susceptible to H-fields with only about fifty percent (50%) shielding effectiveness (SEH=6 dB). For WWAN cell phone TIS EMI testing, this poor performance also frequently requires additional external shielding to boost shielding effectiveness of U/FL wire.
Though it is called micro-wire at 1.37 mm (54 mils typ.) O.D thickness, micro-wire is a relatively thick part particularly to design into a hyper-thin product and particularly when avoidance of pinching during manufacture and repair needs to be taken into account when planning the routing of the micro-wires.
Because many wireless devices today require multiple antennas, multiple wires with are required frequently resulting in haphazard and varied placement of both antennas and wires which each must be individually routed and clipped in place taking many time consuming assembly steps. The wires certainly do not self align. The more steps the greater the chance of error during assembly or repair.
In order to keep the wires in place to avoid damage, cable guides are sometimes employed. Typically cable guides are plastic embosses or clips, which, by definition slightly crush the wire to hold it to the desired routing location. Mounting mechanisms being much too close to the signal inside the wire is both unavoidable and undesirable to performance.
Another design limitation related to the Micro wire relates to its minimum bend radius. Dropping below this radius will cause the cable to kink resulting in the aforementioned performance degradation of the cable. The minimum bend radius for a typical 1.38 mm O.D. Micro Coaxial Cable is 14 mm (which is over 500 mils). In order to comply with this limitation, it is frequently necessary to design a cabling route which is corkscrewing antenna in order to get from one level to another level in the a mobile device level to level. To violate this spec is to essentially, again, ‘kink’ the antenna wire leading to VSWR and performance losses.
Because of the problems associated with the micro-wire cable routing, currently it is atypical to provide a service loop in the RF wire making assembly and repair of the system more difficult. Typically when a service loop is provided it roams into EMI problematic areas requiring additional cable EMI and routing management. A service loop is potentially even more problematic if the service loop enters the actual antenna resonating area(s), affecting or detuning performance.
Current since RF systems are typically delivered with integrated wire tails. It is difficult to service, repair or upgrade these components and frequently requires disassembling of the entire device.
Furthermore, dedicated, non-swappable antennas typical in this industry require longer test periods to have multiple systems and tests support permutations of antennas and radio technology.
Consequently, the flaws and limitations of working with Micro-wire cable create a need for an improved devices and methods of connecting RF devices to other electronic components in a mobile computing device.